Comparison of seroprevalence from different human populations and regions in China.

<p>A) Comparison of the seropositivity of H9N2 viruses in occupationally exposed populations. The seropositivities among different occupationally exposed populations were significantly different for H9N2 viruses (<i>p</i> = 0.0023 for A/Guangzhou/333/99 (G9) and <i>p</i> = 0.041 for A/quail/Hong Kong/G1/97(G1)). B) Comparison of the seroprevalence of H9N2 viruses in different age groups. Children: aged up to 14; Youth: aged 15–24; Adult: aged 25–59; Elderly: aged over 60. The seroprevalences of H9N2 viruses in different age groups were significantly different (<i>p</i><0.0001 for both H9N2 viruses). C) Comparison of the seroprevalence of H9N2 antigens in Northern and Southern China. ** indicates <i>p</i>≤0.001.</p>